Method of making a circuit breaker lever



y 2, 1956 H. v. ELLIOTT 2,746,131

METHOD OF MAKING A CIRCUIT BREAKER LEVER Original Filed April 2, 1949 IN VEN TOR.

(92;? M /7 BYH4ROLD VELLmTT Mmiz HT TaQmEYs United States Patent METHOD OF MAKING A CIRCUIT BREAKER LEVER Harold V. Elliott, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Original application April 2, 1949, Serial No. 85,172, now Patent No. 2,616,011, dated October 28, 1952. Divided and this application August 27, 1952, Serial No. 306,701

7 Claims. (Cl. 29-15555) This invention relates to circuit breakers for ignition timer and more particularly levers of the type shown in C. H. Davis, Jr, Reissue Patent No. 19,083, granted February 13, 1934, and is a division of copending application Ser. No. 85,172, filed April 2, 1949, now Patent No. 2,616,011, issued October 28, 1952.

An object of this invention is to provide a durable circuit breaker lever which operates at high speed without chattering or rebounding of the contacts. To accomplish this, the present invention provides a circuit breaker lever of novel construction and a method of making it. A blank of thin sheet metal of symmetrical shape having holes bounded by annular flanges at right angles to the plane of the blank is folded on its axis of symmetry to provide two leaves from which the annular flanges extend in alignment to provide a hub portion which receives a bearing bushing. The edges of the leaves are shaped to provide flanges which extend from the hub portion to the other or free end of the lever and which extend at right angles to the planes of the leaves. These flanges, which together with the annular flanges stiffen the lever, provide a contact receiving pad at the free end of the lever and a cam follower rubbing block receiving pad intermediate the ends of the lever. A single rivet, which passes through a hole provided by the rubbing block pad and straddles the leaves and is attached thereto, secures to said pad the rubbing block and one end of a leaf spring. Preferably, the rivet is bonded to the leaves by hydrogen brazing in the same operation which brazes the contact to the contact pad.

Further objects and advantges of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Figs. 1 to 8 show the steps of shaping and folding sheet metal to form the lever.

Figs. 9 to 12 show the steps of assembling other parts with the lever.

Fig. 13 is drawn to a larger scale than the preceding figures and show the lever with a rivet attached thereto.

Fig. 14 is a sectional view on line 1414 of Fig. 13.

Fig. 15 shows a side view of the completed lever.

Figs. 16 and 17 are sectional views taken respectively on lines 1616 and 1717 of Fig. 15.

A blank 20 is punched from thin sheet steel for example .010" thick. The depressions 21 therein are formed as shown in Fig. 2 and holes 22 are punched in these depressions as shown in Fig. 3 thereby providing flanges 23 which are shaped to form cylindrical projections 24 (Fig. 4) perpendicular to the plane of the blank 20. The blank 20 is shaped as shown in Fig. and is provided with holes 25. The blank is then folded on its axis of symmetry to provide two leaves 26 which are folded together to form a stiffening rib ice and so that the holes 25 are aligned and the cylindrical flanges 24 are aligned on axis perpendicular to the planes of the leaves 26. The leaves 26 are shaped as shown in Fig. 8 to provide flanges 27 which extend from the hub of the lever to the tip thereof and include pads or platforms 28 in the same plane and at right angles to the plane of the leaves 26 from which extend flanges 29 at right angles to the portions 28 and parallel to each other and to the planes of the leaves 26. The flanges 27 continue from the pad portions 28 to cars 30 which provide a pad for receiving a contact disc. The flange 27 is in part bent diametrically across the holes 25 so that the flanges 28 together provide a hole 31 which includes the two half portions of the holes 25. The other half portions of the holes 25 are shown at 25 in Fig. 13. A rivet 33 is provided with the notch 34 to straddle both leaves 26 and with a bore 35 in its lower end. A rivet 33 is passed through the hole 31. formed of half portions of holes 25 and upwardly as viewed in Fig. 14 so that the notch 34 receives the leaves 26. The rivet 33 is secured to the leaves 26 by spot welding indicated at 36 in Figs. 13 and 14 to hold it in the desired position which is perpendicular to the flange portions 28.

The assembly of lever and rivet is copper plated and is placed in a fixture which holds the contact disc receiving pads 30 in a horizontal plane facing upwardly. The contact disc, preferably tungsten, is placed upon the pads 30 and this assembly is heated in a hydrogen atmosphere to a temperature suficient to cause the copper plate to alloy with parts of the assembly and thus form when the assembly is cooled a permanent bond. The contact 40 is bonded to the lever by a layer 41 of copper alloy the thickness of which is somewhat exaggerated in Fig. 15. A copper alloy bond is formed between the rivet 33 and the leaves 26 and some of the copper plating creeps into the hole 31 and substantially fills it so that the rivet is bonded to the flange portions 28 as well as directly to the leaves 26.

A fiber bushing 42 is pushed into the flanges 24 (Fig. 16) the edges of which are deformed into grooves 43 provided by the bushing. A rubbing block 44 and a leaf spring 45 having holes for receiving the rivet 33 are assembled as shown in Figs. 15 and 17 and thc lower edge of the rivet is deformed at 46 to secure the rubbing block and spring to the lever. The rubbing block fits between the flanges 29 so that it cannot turn on the rivet. A spring 45 is provided with a notch 47 adapted to be received by a suitable terminal support.

The side flanges 27 which extend from the hub of the lever to the tip thereof contribute materially to the rigidity of the lever and thereby make it possible to make a satisfactory lever of sheet steel having thickness as low as .010 inch. Because thin sheet steel is used, the lever is lighter in weight and therefore will perform satisfactorily at high speed without contact rcbound or chattering, for example, at 2500 R. P. M. ignition timer cam speed or 5000 R. P. M. engine speed. Through the use of a single rivet for attaching the rubbing block and the spring to the lever, durability has been increased.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. The method of making a circuit breaker lever which comprises shaping a sheet metal blank in a symmetrical shape desired, punching, adjacent one end of the blank, two holes on a center line at right angles to the axis of symmetry of the blank and equidistant therefrom, then punching intermediate the ends of the blank two Patented May 22, 1956 additional holes on a center line at right angles to the axis of symmetry and equidistant therefrom, folding the blank on its axis of symmetry to provide two integral leaves having the sets of holes in alignment, the first set of holes being at the hub portion of the lever, bending the leaves to provide at the end remote from the first mentioned holes two meeting ears in the same plane and at right angles to the planes of the leaves, bending the leaves on longitudinal center lines across the second mentioned holes to provide two meeting, cam rubbing block receiving pad portions in the same plane and at right angles to the planes of the leaves, said second pad portions providing a hole comprising portions of the second mentioned holes in the blank, assembling with the lever thus formed a rivet which has a notch at one end which receives the leaves and which extends through said holes in the second pad portions, attaching the rivet to the leaves, attaching a rubbing block to the second pad portions by means of the rivet, attaching a contact disc to the ears, and passing a bushing into the first-mentioned holes and securing it to the leaves.

2. The method according to claim 1 further characterized by the steps of copper plating the assembled lever and rivet and mounting a contact disc upon the ears and subjecting the assembly to an elevated temperature in a hydrogen atmosphere to effect the bond ing of the rivet and the contact to the lever by the plating copper.

3. The method according to claim 1 further characterized by shaping of the leaves after folding together to provide continuous flanges extending from the hub portion of the lever to the other end thereof, said flanges being at right angles to the planes of the leaves and including the contact receiving ears and the rubbing block receiving pad portions.

4. The method of making a circuit breaker lever which includes the steps of shaping a sheet metal blank in a symmetrical shape desired, punching intermediate its ends two holes on a center line at right angles to the axis of symmetry of the blank and equidistant therefrom, folding the blank on its axis of symmetry to provide two integral leaves, with the holes in alignment, bending the leaves longitudinally across said holes to provide meeting flanges in the same plane and at right angles to the planes of the leaves, said flanges together providing a hole comprising portions of the holes in the leaves, assembling with the lever thus formed a rivet which has a notch at one end which receives the leaves and which extends through said holes in the second pad portions, attaching the rivet to the leaves, and then attaching a rubbing block to the flanges by means of the rivet.

5. In a method of making a circuit breaker lever including a rubbing block and a mounting bushing thereon, the steps comprising; shaping a blank of sheet metal in a symmetrical fashion and to a shape desired, punching apertures in said blank for providing two pairs of holes wherein each pair of holes is on an axis at right angles to the axis of symmetry of the blank and wherein each hole of respective pairs of holes is spaced equidistant to said axis of symmetry, folding the blank along the axis of symmetry, bending symmetrical portions of said folded blank substantially at right angles to the plane of the folded blank wherein each of said bent portions includes a portion of one hole of one of said pairs of holes, bending the longitudinal edges of said portions back into a plane parallel to the plane of said folded blank, assembling a rubbing block in juxtaposed relation to the symmetrically bent portions and between the longitudinally bent edges thereof for holding the folded blank together by association with said one pair of holes, and finally assembling a bushing through the other pair of holes.

6. in a method of making a circuit breaker lever including an apertured rubbing block and a mounting bushing thereon, the steps comprising; shaping a blank of sheet metal in a symmetrical fashion and to a shape desired, punching apertures in said blank for providing two pairs of holes wherein each pair of holes is on an axis at right angles to the axis of symmetry of the blank and wherein each hole of respective pairs of holes is spaced equidistant to said axis of symmetry, folding the blank along the axis of symmetry, bending symmetrical portions of said folded blank substantially at right angles to the plane of the folded blank wherein each of said bent portions includes a portion of one hole of one of said pairs of holes, bending the longitudinal edges of said portions back into a plane parallel to the plane of said folded blank, positioning the apertured rubbing block on said bent portions and in juxtaposed relation therei-vith and spaced between said longitudinal edges thereof, passing a split shank rivet through the aperture in said block over said bent portions for inserting the split portion of the rivet through said pair of holes so as to straddle opposite sides of the folded blank, welding said rivet shank to said folded blank and finally assembling the bushing through said other pair of holes.

7. In a method of making a circuit breaker lever including an apertured rubbing block thereon, the steps comprising; shaping a blank of sheet metal in a symmetrical fashion and to a shape desired and punching apertures on said blank for providing two pairs of holes wherein each pair of holes is on an axis at right angles to the axis of symmetry of the blank and wherein each hole of respective pair of holes is spaced equidistant to said axis of syrrlnetry, folding the blank along the axis of symmetry, bending symmetrical portions of said folded blank substantially at right angles to the plane of the folded blank wherein each of said bent portions includes a portion of one hole of one of said pairs of holes, bending the longitudinal edges of said portions back into a plane parallel to the plane of said folded blank, positioning the apertured rubbing block on said bent portions and between said longitudinal edges, passing a split rivet through the aperture in said block over said bent portions for inserting the split portion of said rivet through said pair of holes so as to straddle opposite sides of the folded blank, and then welding said rivet to said folded blank.

References (Iited in the file of this patent UNITED STATES PATENTS 956,666 Auel May 3, 1910 1,851,568 Davis Mar. 29, 1932 1,985,573 Mallory Dec. 25, 1934 2,025,191 Davis Dec. 24, 1935 2,673,273 Vasold Mar. 23, 1954 

